4. Sean Bean
Yeah, that's right...GoldenEye's 006 was very nearly 007. Back when a replacement for Timothy Dalton was being searched for, Sean Bean auditioned for the role, making it so far as becoming EON's second choice.
Unfortunately for Bean, Pierce Brosnan had auditioned too, impressing the producers just a little bit more. Nevertheless they were keen to keep Bean around, giving him the part of the villain, Alex Trevelyan.
Interestingly, 006 was originally supposed to be Bond's mentor, but the part was rewritten to become Bond's villainous parallel, owing to how much Bean had impressed producers during his audition for the role of 007.